Compressed-air brake



May 7 1929- A. ANDERBr-:RG ET AL 1,712,016

' COMPRESSED AIR BRAKE Filed'vJan. 9, 1928 Patented May 7, 1929. i

UNlTED STATES annees Annemans Ann ERIK Nouns Aivnnanne, or` Manno, SWEDEN, v,Asn c siemens 'ro anni, nonnrsnnss MnKANIsKA vnnnsrans Anrrneonns, 0F LUND, f swnnnn, n CORPORATION or SWEDEN. Y f

PATENT oFFoICEeT* conrnnssnnnrn BRAKE.

Application ,file d January 9,`1928, Serial No. 245,540, and in Swedenbeeember 163119,93.k

@ur present invention refers to an improvement in compressed air brakes and more speeilically to a device for acceleration of the velocity of `propagation of the decrease in pressure, within the main brake pipe when braking. p c' An acceleration device of this kind is an arrangement lier the purpose of removing the volume or body of air displaced by the piston of the rcontrol valve or triple valve from the system when braking, so that such air is not carried back to the main pipe, which circumstance, in the case of long trains comprisinga large number of braking cars and a correspondingnumber ot control valves, might cause an unintentional increase in pressure within the main pipe, thereby raising the pressure once decreased for the purpose of braking, so that the advancing movement .of the brake shoes is delayed, especially nearest to the rear end of the train. 1

The way which first suggests itself for obtaining such a function is, oil course, to arrange within the control valve a cavity or chamber which is connected to the main pipe and int-o which the stroke volume or the control piston is transferred whenbrak-r ing and thereafter permitted to escape to the atmosphere when releasing` the brakes simultaneously with an interruption or the connection between said chamber and the con. trol valve. This solution of the problem has also been previously. proposedbuty it malice necessary substantial changes in the construction or they control valve' housing,` and; its slide valve member, which latter must be provided with cavities and openings ,tor connection of the Vchamber alternately with the main pipe and withthe atmosphere according to the position of the control piston for said slide valve member. ln practice these conditions make it impossible to carry out the changes needed without av complete substitution of the old control valve as a whole by a new valve provided with the acceleration arrangements.

The present invention has for itspurpose to do away with this'drawbacl by providing an acceleration device which, without any alteration at all of the control valve housingor its controlmembers, may be applied to the known control `valves alreadyin ilse.

lin the following, the,invention will be described with reference'toithe accompanyh ing drawing which shows the same applied to a control valve of the lrind described in our rprior Patent No.`1,663,579,,butfit will be obvious to anyone skilled in the art that the invention may be combined equally 'well with any other control valve structure rhav,- ingl a reciprocable control piston por] the like, for instance a diaphragm, the moveL ments of which will cause a displacement of a certain quantity of Vain-The drawing shows the control valve and the acceleration attachment 'in longitudinal section, the

parts of the brake-system having' no direct connection with the invention being representedin dotted lines. i

The K acceleration device according,r tothe invention is intended to be positioned as a whole at that end'of the,,control"chamber"orv cylinder ofthe control valve which'is conH nected to the main pipel so as to forni aicovler on said chamber at that end, ,and 'according' tov'the construction illustinitedsaidv cover l made vin the form ont a cylinder for' a tightly fitting' reciprocable ypiston 2 provided M with a hole ll placed suitably atthe cent-ral portion of the piston and'extending through the same in L direction. The control piston 2l is provided' with a piston rodv having.,f a portion Skwhich extends downwardly below the piston and 'carries a cross-pin 4,.

constantly tends i to` push the valve as fark away as possible from theAv piston 24, the lowerend position `ofthe valve being determined by the means clescribeclnbove, `The valve Z is placedin axial alignment withithe hole 1l in piston2 and serves as a means for closing the same will be described below; k The piston 2 is constantly pressed toward the control piston 24 by means of a .return spring 8` and its upward movement islimited by suitable ab,utments,"so'thatl said piston 2 normally forms` thel bottom Wall of the control piston cylinder, whichbfottom' is normally open to the space below the piston 2 by means of the hole 11. The piston 2 is further provided with one or more radial holes or ports 9 coacting with corresponding holes or ports l0 in the wall of the cylinder l for the purpose of establishing communication between the interior of the said cylinder below the piston 2 and the atmosf phere when the piston is moved downwardly in the manner described below.

The control valve structure is connected by Vmeans of the nipple 25 with the main pipe P and by means of the nipple 2G with the auxiliary air reservoir A or its equivalent, such as for instance a so-called working chamber, and said valve structure is provided with lchannel 29 leading to the working chamber of the brake device B, a channel 3() leading to the atmosphere and a channel 35; leading to the function chamber of the "brake,

The operation of the device is as follows In the drawing the parts of the valve structure are shown in the positions which they assume when the brakes are released, i. e. a condition in which the brakesA are loaded and ready for braking-lVhen braking, the pressure within the main pipe P is decreased by a suitable manipulation of the drivers valve (not shown) and thereby the pressure beneath the piston 24 is also decreased. Then the pressure within Athe auX- iliary air reservoir A in va manner known per se will push down the piston-24, so that the known feed groovey 27 is closed, this movement corresponding to the distance between the upper end of the upper spring 3l and the abutment 32 on the control piston rod. At the end of this movement of the piston 24, the valve 7 comes to rest against a seat arranged around the hole 11 in the piston 2, and during the continued downward movement of the piston 24 the spring G will be compressed to a degree limited by the pin 4 and the slots in the sleeve 5. Thereafter the piston 2 must join in the downward movement of the piston 24 and then the ports 9 and l() come into register with lthe result that the air at present beneath the piston 2 escapes tothe atmosphere, the piston 2 being further pressed down by means of the piston 24 and the higher pressure at hand on the upper side of the same, until the lowermost position is reached in which the ports 9, 10 are still in register. Simultaneously with the piston 2 the piston 24 has also moved downwardly until its lowest position is reached, and it will be obvious that even if the piston 24 should lag behind in the downward movement the hole 1l nevertheless will not be opened, since the spring 6 in the manner described above has been compressed and pressesV the valve 7 against its seat.

Anyv difference in velocity of movement of the pistons 2 and 24 will thus be equalized by the spring 6, and in this connection it will be noted that the velocity of the piston 2 at the downward movement is dependent on the free area of the coacting holes 9 .and l0 which easily may be altered at will.

In the operation just described the piston 24 has thusmoved downwardly and compressed the upper spring 3l, the spring pressure thus accumulated being sufficient to overcome the retarding action of the arresting means ,33 on the slide valve 23 and thus carry said valve to its lower position in which the channel 29 is open so that air from the auxiliary air reservoir A is admitted to the brakes-The increase in pressure which otherwise would have arisen in the main pipe due to the downward movement of the piston is equalized by the downward movement of the piston 2 increasing the main pipe volume as a whole, and the diameter of the piston 2 is of course to be chosen in such a manner that its stroke volume is equal to or even somewhat greater than the stroke volume of the piston 24.

@n releasing the brakes no change ini-the position of the diiferent parts as described occurs until the pressure within the main pipe l? has been increased to a value higher than the pressurewithin the 'auxiliary air reservoir A. lllhen this difference is obtained, the piston 24 will be pressed upwardly again whereby the valve 7 will be kept closed as long as the pin 4 moves freely in the slots of the sleeve 5. Then such free movement is no lono'er possible the hole 1l is opened and the pressure is transmitted also to the under side of the piston 2 which then moves upwardly aided also by the spring 8. The velocity of this upward movement of the piston 2 is of course dependent on the free area of 'the hele 1l which also may be altered at will.

It will thus vbe obvious that the space below the piston 2 will not receive a charge of compressed air until during the last pcriod of the releasing of the brakes. This means an advantage, because during the gradual alterations of the baking force, which oftentimes must be used after the brake shoes have been advanced towards the wheels, the acceleration device will, of course, not be responsive to the smaller alterations in pressure, since a reverse condition would cause an unnecessary consumption of compressed air.

As will be understood at once from the drawing, the acceleration device according to the invention may be mounted on control valves already in use without any alteration of the valve structure at all. The cover which is always arranged beneath the piston 24 maybe removed and replaced by the member l forming the acceleration cylvalves in use, since it has for its general purpose to 'facilitate the Withdrawal of the piston 24 from itscylinder for inspection purposes. A

From the foregoing it will also be noted that the invention, from the standpoint of L ments previously proposed Jtor the same purpose, but that the mode of operation and the structural 'features of the invention "for obtaining` its object are entirely diiierent from those of earlier constructions. The advantages gained by the invention Will be most clearly seen from thek fact that the same at Aa minimum oli expense may be applied to old control valves already in use, but when consideringl also thefact that not all oi the control valves need to be provided With any acceleration device theA invention involves also the advantage that all ot the valves may be constructed in the same manner,vvhether they are intended to be provided with acceleration device or not, the difference being; an additional feature only, and this 1fact means a great advantage in the manufacture ot the valves and in the accessibility ot spare parts.

lt is obvious that the attainment of these advantages must imply the application oit a completely new principle of connection, and in the present case there cannot be said to -bc any special transfer chamber, since the same is normally in free communication with the control valve cylinder and besides at the movement of the control'piston it changes its volume; nor can it be said that such a chamber, as in the known arrangen ments, is brought into communication with Athe main pipe during; braking, since the communication ispresent previous to the braking and is broken or interrupted when braking occurs.

The embodiment shown in the drawing` for the purpose otezqilaining` the invention has been chosen :in order to make the in` vention clearly understood, but in practice the constructioiial features described may be varied in many Ways, the main point being the expansible chamber at that side oi'i the control piston acted upon by the main `pipe pressure. The means for tightening the acceleration piston may also be constructed in many ways, and the same is true With regard to the means for connecting the space below said piston with the atmosphere, as Well as the means tor closing` the hole through said piston when the control piston has moved through so great a part ot its stroke that the feed grooves 27 are closed.

Both the control piston 24 and the acceleration piston 2 or either of them, for instance the latter piston, may of course be replaced its function, is analogous to the arrange by equivalents, such as for instance diaphragms,y and although the invention has been described above in connection with the usual control; valve or' triple valve, `which connection no doubt Will be the most common one in practice, thereis nothing to prevent the invention from also beingused in connection with other control means acted upon by the main pipe pressure, even ifsuch control means are of a special nature vand coupled'to the brake system for the purpose of actuating` the acceleration deviceonly.

Vilhat We claim is l. In `a compressed air brake system, a main brake pipe, a movable control member actuated by the pressure Within said main pipe, a chamber surroundi said control member, a movable Wall confining said chamber jand determining the volumeot the same, and means connected with the control member and actinorupon said movableivall for increasing the volume of said chamber in proportion to the decrease ot the same due to the movement of the control member caused by a decrease in pressure Within the main pipe. r

' 2. In a compressed air brake system, a main pressure pipe, a compressed aircliamber, a movable control member acted upon at one side by the pressure Within the main pipeand atthe other side by the 'pressurey 'Within said chamber so as to movek in correspondence with the differences in pressure, an acceleration chamber connected to the main pipe, a movable acceleration member arranged in said last mentioned chamber and dividing the same in tWo parts, normally open communication means between both Vparts of the acceleration chamber, valve means for closing said'communicationy means, interconnecting"means between the movable controlniemberand said valve means'tor the purpose oif closing the latter during theA movement of the control member caused by a decrease in pressure Within the main pipe, means for causing' the acceleration member to move in unison with the control member ai'ter the said valve means has been closed, and means for exposing the accelerationchambcr to the atmosphere during` the movement of the acceleration member and at that side oi'' said member not acted upony by the main pipe pressure after the closing ot the aforesaid valve means.

3. In a compressed air brake system, a movable controly member, a main pressure pipe, means tor conveying the pressure With-r in the said pipe to one side of said convtrol member, a compressed air chamber, vmeans for conveying' the pressure Within said chamber to the other side of the control member, an acceleration cylinder connected to the main pipe, a movable acceleration piston reciprocably arranged in said cylinder and having a normally open aperture forme lll) ing a communica-tion channel between both sides of the same, valve means for closing said communication channel, interconnecting` mea-ns between the control member and said valve means for the purpose ot closing` the same during the movement of' the control member caused by a decrease in pressure within the main pipe, means for causing the acceleration piston to move in unison with the control. member after the said valve means has been closed, and means for ex-posing; the interior of the acceleration cylinder to the atmosphere duringthe travel of the acceleration piston and at that side oit said piston not acted upon by the main pipe pres sure after closing of the aforesaid valve means. v

et. ln a compressed air `brake system, a main pressure pipe, a compressed air chamber, a. movable control piston reciprocably positioned within a corresponding` cylinder and acted upon at one side by the pressure within the main pipe and at the other side by the pressure within said air chamber so as to move in correspondence with the differences in pressure, an acceleration cylinder placed in axial alignment with the control piston cylinder in free communication with the latter at that end of the same connected to the main pipe, an acceleration piston reciprocably positioned within the acceleration cylinder and (ilividing the same in two chambers, normally fopen communication means between both sides of the acceleration piston, valve means for closing` said communication means, interconnecting,` means between the movable control pistonand said valve means ior theV purpose of closing the latter during` the movement ot the control piston due to a decrease in lpressure within the main pipe, means for causing,` the acceleration piston to move in unison with the control piston atter the said valve means has been closed, and

means for exposing the acceleration cylinder to the atmosphere during the movement ot Vthe acceleration piston and at that side of the same shut oit from the main pipe after the closing` of the aforesaid valve means.

5. In a compressed air brake system, a main pressure pipe, a compressed air chambei', a movable control piston reciprocably positioned within a corresponding cylinder and acted upon at one side by the pressure within the main pipe and at the opposite side by the pressure within said air chamber, an acceleration cylinder placed in the direct elongation of the control piston cylinder and forming' a cover ttor the latter at that side of the same connectedfto the .main pipe, an acceleration piston reciproeably positioned within the acceleration cylinder and divid-.

i ng the same in two chambers, normally open communication means between both sides of the acceleration piston, valve means slidably connected with the acceleration piston in position for closing said communication means when 4the control piston is moved towards the acceleration piston, springmeans for advancing said valve means towards the accelerationpiston, spring means for advancingv the acceleration piston towards the control piston, means for limit-ing the sliding' movement between the valve means and the control piston so as to cause a movement of the acceleration piston in unison with the control piston, and means for exposing the acceleration cylinder to the atmosphere durmg the movement of the acceleration piston .and at that side ot the same shut oil' from the main pipe after the closing of the aforesaid valve means.

'In testimony whereof we have siOned our names to this speeilieation.

Amiens Annemasse. nam Annees Anneliese@ 

